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91.
通过对两间小学639名学生进行微量元素检测及体格检查,并进行中医辩证分型,发现广州市部份小学生体内微量元素缺乏较严重,占体检总人数的62.3%,同时也存在营养不良,贫血、佝偻病,急慢性上呼吸道炎等、按中医辩证分型有肝热、脾气虚弱、肝血不足、肾气虚等,本文试从微量元素缺乏与中医辩证中找出两者之间的联系,以便于指导治疗,提高小学生的健康水平,增强体质和智力。  相似文献   
92.
微量元素对人体健康的影响   总被引:15,自引:2,他引:15  
阐述了微量元素的生理作用以及对人体健康的影响和微量元素平衡的重要性,对临床医学及日常生活有一定的参考价值。  相似文献   
93.
Zusammenfassung Eine ausgeprägte Strangaufweitung tritt bei anorganischen Glasschmelzen dann auf, wenn bei schleichender Strömung eine Haftung zwischen der Wand des Matrizenkanals und dem strömenden Medium gegeben ist. Sie rührt dabei von der Umorientierung der Geschwindigkeitsverteilung von einem parabelförmigen zu einem kastenförmigen Profil her.In den experimentellen Untersuchungen konnte festgestellt werden, daß oberhalb einer bestimmten Kanallänge, d. h. bei ausgeprägten Strömungsverhältnissen im Preßwerkzeug die flächenbezogene Strangaufweitung konstant und dabei insbesondere unabhängig von der Profilform etwa 29% beträgt. Daraus wird gefolgert, daß dieser Betrag dem linearen Wert für den zweidimensionalen Fall des unendlich ausgedehnten Spaltes entsprechen muß.In einer theoretischen Analyse wurde die Berechnung dieses Falles ausgehend von der Stokes-Gleichung mit Hilfe der Methode der finiten Elemente durchgeführt. Aus der sich daraus ergebenden Druck- und Geschwindigkeitsverteilung konnte schließlich die Kontur des austretenden Stranges sowie dessen Endhöhe ermittelt werden.Ein Vergleich der experimentell und rechnerisch ermittelten Werte für die Strangaufweitung zeigt dabei eine recht gute Übereinstimmung und bestätigt dadurch auch die weitgehende Unabhängigkeit der flächenbezogenen Aufweitung von der Querschnittsform des Stranges.
Inorganic glass melts are showing a characteristic die swell, when in the case of slow motion a strong adhesion between the streaming fluid and the wall of the die channel exists. The reason for this phenomenon is the rearrangement of the velocity profile from a parabolic to a box-type design form.The experimental investigations have demonstrated, that above a certain channel length, this means at distinct flow conditions inside the die channel, the value for the extension of the cross-sectional area is constant of about 29%. Particularly it is independent of the shape of the used die profiles. From this result, it is to deduce that this value must correspond to that of the two-dimensional case of the infinite extended slit.In a theoretical analysis the computation of this case was performed, starting from the Stokes-equation by the finite element method. By means of the resulting pressure and velocity distribution, the contour of the emerging rod and its final thickness could be determined.A comparison between experimental and computational results shows good agreement. So the appreciable independence of the magnitude of the die swell from the profile of the extruded rod is confirmed.

A Fläche - a p ,a u Knotenpunktsvariablen für Druck bzw. Geschwindigkeit - a, b Seitenlängen des Rechteckprofils - B =L · N u Matrix - D Viskositätsmatrix - f Kräftematrix - K Schwerkraftvektor - K p ,K u Elementdruckmatrix, Elementgeschwindigkeitsmatrix - L Transformationsmatrix für den ebenen Fall - m Kronecker-Symbol für den zweidimensionalen Strömungszustand - N p ,N u Ansatzfunktionsmatrizen für Druck bzw. Geschwindigkeit - p Preßdruck - R Radius - T Preßtemperatur - t Lastvektor - u = (w, v) Geschwindigkeitsvektor - A flächenbezogene Strangaufweitung - R Aufweitung einer linearen QuerschnittsabmessungR - dynamische Viskosität - Dichte - D u/Dt Substantielle Ableitung der Geschwindigkeit nach der Zeit - T Transponierte einer Matrix (oberer Index) Vorgetragen auf der Jahrestagung der Deutschen Rheologischen Gesellschaft in Berlin vom 13.–15. Mai 1985  相似文献   
94.
On the basis of the structures and properties of the ClO/ClO? system obtained at the density functional theory (DFT) (UB3LYP) level, employing the 6‐311+G(3df) standard basis set, the electron transfer reactivity of this system is investigated. The results indicate that there are five possible stable coupling complexes that correspond to the generous minima on the global potential energy surfaces (PES). The most stable coupling complex is planar EC4, in which there is a O? O linkage with two trans‐Cl atoms. Their stabilization energies are calculated to be 20.57 (EC1: C1), 20.54 (EC2: C2, 2B), 20.69 (EC3: C1), 20.70 (EC4: Cs, 2A′), and 20.69 (EC.5: C2h, 2Bu) kcal/mol at the B3LYP/6‐311+G(3df) level; with the correction of the basis set superposition error (BSSE), the stability order of these encounter complexes is EC4 > EC.5 > EC3 > EC1 > EC2. Based on the five encounter complexes, five coupling modes are designed for the study of the electron transfer reactivity of this system. The dissociation energy curves at the activated states and the corresponding activation energies of these five coupling modes are obtained and are compared at the B3LYP/6‐311+G(3df) and MP2/6‐311+G* levels. The inapplicability of DFT methods has also been discussed in this article in predicting the energy curves, especially with a long contact distance, in which DFT methods give the abnormal behavior for the dissociations of the complexes caused by the “inverse symmetry breaking” problem. On the basis of the golden rule of the time‐dependent perturbation theory, the electron transfer reactivity and the contact distance dependence of the various electron transfer kinetics parameters (e.g., activation energy, coupling matrix element) have been analyzed at the UMP2(full)/6‐311+G* level. The electron transfer can take place over a range of contact distances, but the most effective coupling distance corresponds to only a small range. The coupling orientation analyses also indicate that the most favorable coupling mode to the electron transfer does not always correspond to the most stable encounter complex mechanism. Some highly energetic coupling modes are more favorable for the electron transfer. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005  相似文献   
95.
对抚州地区秀茶场产的茶叶进行了微量元素测定,提供了五种茶的微量元素谱,同时还对比了秀谷茶场产茶和英德红茶中的微量元素含量的差异。  相似文献   
96.
The impedance of zinc-rich polymer coatings on steel in a 3-% NaCl solution is studied. The electrochemical behavior of the electrode is satisfactorily described by an equivalent circuit that contains a constant-phase element, which reflects fractal properties of the zinc surface in the binder. From the results of calculations of the circuit elements for metal-rich electrodes with different zinc contents computed are fractions of the active area of the surface of the coating and its fractal dimensionality.  相似文献   
97.
The conditions of formation of Y, La and lanthanide (from Ce(III) to Lu) enanthates were worked out, their composition and their solubilities in water at 291 K were determined, and the conditions of their thermal decomposition were studied. They were prepared as crystalline solids with general formula Ln(C7H13O2)3·nH2O, wheren=2–10. On heating, they decompose in two or three steps. They first lose some water molecules and then decompose to the oxides directly (salts of Y and heavy lanthanides) or via the intermediate formation of Ln2O2CO3 (salts of La, Pr, Nd, Sm and Eu). Only yttrium enanthate dihydrate loses 2 water molecules on heating to form an anhydrous complex, which decomposes directly to Y2O3. The temperatures of dehydration are similar for all complexes (323–343 K), while the temperatures of oxide formation vary irregularly from 823 K for CeO2 to 1078 K for La2O3.  相似文献   
98.
微波消化技术在生物微量元素测定中的应用   总被引:6,自引:0,他引:6  
用微波消化技术消化了多种食物样品.与传统的干、湿消化法相比,微波消化更加简单、快速、节省、沾污少、损失少、环境污染少.用原子吸收测定样品中的Fe,C.V<2%,加标回收率为98%~100%,测定美国生物标准物质牛肝中的Fe的相对误差为0.3%,结果令人满意.  相似文献   
99.
Preparation and Characterization of Nano-ZnFe2O4/TiO2 Films   总被引:1,自引:0,他引:1       下载免费PDF全文
The nano-ZnFe2O4/TiO2 films possess the functions of desulfurization and degradation for organic pollutants. The sols of ZnFe2O4/TiO2 were prepared by sol-gel method and coated on glass and porous ceramic by vertical coating and dipping-lift processes, respectively, and the samples were obtained after drying and sintering. The composition, appearance, absorption spectrum of the films, and the influence of the film on porous ceramic performances were analyzed using SEM, AFM, UV-Vis spectrometer, and mercury porosimeter, respectively, to determine the operation parameters of the multifunction porous ceramic elements for gas-purification.  相似文献   
100.
研究了用5mol/L盐酸煮沸提取烟叶中的部分金属元素,用ICP-AES测定浸提液,K、Ca、Mg、Cu、B、Ba、Zn获得了较满意的结果,P、Fe、Mn的测定结果稍微偏低。此方法操作简便、快速安全,特别适合大批量烟草样的快速检测。与硝酸-高氯酸湿消化法进行对照,结果吻合得较好。并测定了国家烟草标准样品GBW08514和GBW08515,其结果与标准值相符。  相似文献   
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